1. Field of the Invention
This invention relates to novel boron-siloxane acetylenic or boron-silane acetylenic polymers.
2. Description of the Previously Published Art
Thermally stable polymeric elastomers consisting of alternating carborane and siloxane groups are known for both the deca- and penta-carboranes (HCB.sub.10 H.sub.10 CH and HCB.sub.5 H.sub.5 CH respectively). See, for example, U.S. Pat. No. 3,463,801. Some have been produced commercially. However, these materials do not contain alkynyl moieties such as acetylenic groups or any other functional group for crosslinking purposes to produce thermosetting polymers. These poly(carborane-siloxane) elastomers show superior thermal (high chars) and oxidative properties (low weight loss) at elevated temperatures (900.degree. C.) compared to analogous poly(siloxanes) as monitored by TGA.
Silylene or siloxane-acetylene and silylene or siloxane-diacetylene polymers have also been reported. See, for example, U.S. Pat. No. 5,483,017. Good quality fibers can be drawn from the melts of the silylene-based polymers (visual melt ca. 120.degree. C.) and the fibers can be crosslinked either thermally or with UV light, but they lack the thermally and oxidatively stable boranyl units of the present invention.
More recently, linear inorganic-organic hybrid polymers containing acetylenic and either bis(silyl or siloxyl)carboranyl units or a random distribution of both bis(silyl or siloxyl)carboranyl and bis(silyl or siloxyl) units have been described and are under development at the Naval Research Laboratory. See, for example, U.S. Pat. No. 5,272,237. However, these polymers contain carborane units in each repeating unit which add to their cost.
More recently, less costly copolymers containing a random distribution of both carborane-siloxane acetylenic and siloxane or silane acetylenic units have been synthesized and are under investigation at the Naval Research Laboratory.
3. Objects of the Invention
It is a object of this invention to provide boron-siloxane acetylenic polymers or boron-silane acetylenic polymers hereafter referred to as novel copolymers which are extremely easy to process into thermosets since in the preferred forms they are either liquids at ambient temperature, low melting solids, or low temperature processing glassy materials.
It is a further object of this invention to provide a method for the syntheses of these novel copolymers in a simple one-pot reaction which proceeds in high yield.
It is a further object of this invention to provide a method for the syntheses of these novel copolymers by controlling the ratio of reactants in the syntheses so that different percentages of boron and silicon can be obtained in the resulting copolymer.
It is a further object of this invention to provide a method for the syntheses of these novel copolymers by controlling the relative amount of the boron and silicon units to the alkynyl unit depending on the physical properties desired.
It is an further object of this invention to provide for novel linear polymers that are soluble in most organic solvents so as to be useful in structural, microelectronic, and nonlinear optical (NLO) applications.
It is a further object of this invention to provide for novel copolymeric precursors which are used for making both high temperature, oxidatively stable thermosets and ceramics.
It is a further object of this invention to provide for novel copolymeric precursors which are cross-linkable by thermal or photochemical means through the triple-bonds of the acetylenic units to form thermosetting polymers.
It is a further object of this invention to provide novel copolymers which eliminate the carborane component and replace it with a simple aryl substituted boron unit in the copolymer while still retaining excellent thermal and thermooxidative stabilities at elevated temperatures.
It is a further object of this invention to provide novel polymeric materials which provide the desirable features of inorganics at elevated temperatures such as high thermal and oxidative stability and the desirable features of organics such as processability.
It is a further object of this invention to provide novel copolymers which contain silyl, and/or siloxyl, and/or aryldisilyl, boranyl, and acetylenic units in the backbone.
It is an further object of this invention to provide novel copolymers containing flexible siloxane or silane units which maintain processability in the copolymer and which also contribute to high temperature stability due to their own inherent thermal stability.
It is a further object of this invention to provide novel boron-silicon-acetylenic containing polymers having superb processability and outstanding thermal and oxidative stability due to the organic constituents and due to the unique combinations of boranyl and siloxane or silane units, respectively.
It is a further object of this invention to provide novel copolymers which contain silyl and boranyl units and which exhibit electrical conductivity properties and which are suitable for use in the microelectronic industry and for use as nonlinear optical materials (NLO).
It is a further object of this invention to provide novel copolymers with various electrical properties which can be easily synthesized by varying the substituents on both the boron and silicon units.
These and further objects of the invention will become apparent as the description of the invention proceeds.